Memory arrays and methods used in forming a memory array comprising strings of memory cells

ABSTRACT

A method used in forming a memory array comprising strings of memory cells comprises forming a stack comprising vertically-alternating first tiers and second tiers. Horizontally-elongated trenches are formed into the stack to form laterally-spaced memory-block regions. A wall is formed in individual of the trenches laterally-between immediately-laterally-adjacent of the memory-block regions. The forming of the wall comprises lining sides of the trenches with insulative material comprising at least one of an insulative nitride and elemental-form boron. A core material is formed in the trenches to span laterally-between the at least one of the insulative nitride and the elemental-form boron. Structure independent of method is disclosed.

TECHNICAL FIELD

Embodiments disclosed herein pertain to memory arrays and to methodsused in forming a memory array comprising strings of memory cells.

BACKGROUND

Memory is one type of integrated circuitry and is used in computersystems for storing data. Memory may be fabricated in one or more arraysof individual memory cells. Memory cells may be written to, or readfrom, using digitlines (which may also be referred to as hitlines, datalines, or sense lines) and access lines (which may also be referred toas wordlines). The sense lines may conductively interconnect memorycells along columns of the array, and the access lines may conductivelyinterconnect memory cells along rows of the array. Each memory cell maybe uniquely addressed through the combination of a sense line and anaccess line.

Memory cells may be volatile, semi-volatile, or non-volatile.Non-volatile memory cells can store data for extended periods of time inthe absence of power. Non-volatile memory is conventionally specified tobe memory having a retention time of at least about 10 years. Volatilememory dissipates and is therefore refreshed/rewritten to maintain datastorage. Volatile memory may have a retention time of milliseconds orless. Regardless, memory cells are configured to retain or store memoryin at least two different selectable states. In a binary system, thestates are considered as either a “0” or a “1”. In other systems, atleast some individual memory cells may be configured to store more thantwo levels or states of information.

A field effect transistor is one type of electronic component that maybe used in a memory cell. These transistors comprise a pair ofconductive source/drain regions having a semiconductive channel regionthere-between. A conductive gate is adjacent the channel region andseparated there-from by a thin gate insulator. Application of a suitablevoltage to the gate allows current to flow from one of the source/drainregions to the other through the channel region. When the voltage isremoved from the gate, current is largely prevented from flowing throughthe channel region. Field effect transistors may also include additionalstructure, for example a reversibly programmable charge-storage regionas part of the gate construction between the gate insulator and theconductive gate.

Flash memory is one type of memory and has numerous uses in moderncomputers and devices. For instance, modern personal computers may haveBIOS stored on a flash memory chip. As another example, it is becomingincreasingly common for computers and other devices to utilize flashmemory in solid state drives to replace conventional hard drives. As yetanother example, flash memory is popular in wireless electronic devicesbecause it enables manufacturers to support new communication protocolsas they become standardized, and to provide the ability to remotelyupgrade the devices for enhanced features.

NAND may be a basic architecture of integrated flash memory. A NAND cellunit comprises at least one selecting device coupled in series to aserial combination of memory cells (with the serial combination commonlybeing referred to as a NAND string). NAND architecture may be configuredin a three-dimensional arrangement comprising vertically-stacked memorycells individually comprising a reversibly programmable verticaltransistor. Control or other circuitry may be formed below thevertically-stacked memory cells. Other volatile or non-volatile memoryarray architectures may also comprise vertically-stacked memory cellsthat individually comprise a transistor.

Memory arrays may be arranged in memory pages, memory blocks and partialblocks (e.g., sub-blocks), and memory planes, for example as shown anddescribed in any of U.S. Patent Application Publication Nos.2015/0228659, 2016/0267984, and 2017/0140833, and which are hereby andherein fully incorporated by reference and aspects of which may be usedin some embodiments of the inventions disclosed herein. The memoryblocks may at least in part define longitudinal outlines of individualwordlines in individual wordline tiers of vertically-stacked memorycells.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic cross-sectional view of a portion of asubstrate in process in accordance with an embodiment of the inventionand is taken through line 1-1 in FIG. 2.

FIG. 2 is a diagrammatic cross-sectional view taken through line 2-2 inFIG. 1.

FIGS. 3-13 are diagrammatic sequential sectional and/or enlarged viewsof the construction of FIGS. 1 and 2, or portions thereof, in process inaccordance with some embodiments of the invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Embodiments of the invention encompass methods used in forming a memoryarray, for example an array of NAND or other memory cells havingperipheral control circuitry under the array (e.g., CMOS-under-array).Embodiments of the invention encompass so-called “gate-last” or“replacement-gate” processing, so-called “gate-first” processing, andother processing whether existing or future-developed independent ofwhen transistor gates are formed. Embodiments of the invention alsoencompass a memory array (e.g., NAND architecture) independent of methodof manufacture. Example method embodiments are described with referenceto FIGS. 1-13 which may be considered as a “gate-last” or“replacement-gate” process.

FIGS. 1 and 2 show a construction 10 having an array or array area 12 inwhich elevationally-extending strings of transistors and/or memory cellswill be formed. Construction 10 comprises a base substrate 11 having anyone or more of conductive/conductor/conducting,semiconductive/semiconductor/semiconducting, orinsulative/insulator/insulating (i.e., electrically herein) materials.Various materials have been formed elevationally over base substrate 11.Materials may be aside, elevationally inward, or elevationally outwardof the FIGS. 1 and 2-depicted materials. For example, other partially orwholly fabricated components of integrated circuitry may be providedsomewhere above, about, or within base substrate 11. Control and/orother peripheral circuitry for operating components within an array(e.g., array 12) of elevationally-extending strings of memory cells mayalso be fabricated and may or may not be wholly or partially within anarray or sub-array. Further, multiple sub-arrays may also be fabricatedand operated independently, in tandem, or otherwise relative oneanother. In this document, a “sub-array” may also be considered as anarray.

A conductor tier 16 comprising conductive material 17 has been formedabove substrate 11. Conductor tier 16 may comprise part of controlcircuitry (e.g., peripheral-under-array circuitry and/or a common sourceline or plate) used to control read and write access to the transistorsand/or memory cells that will be formed within array 12. A stack 18comprising vertically-alternating insulative tiers 20 and conductivetiers 22 has been formed above conductor tier 16. Example thickness foreach of tiers 20 and 22 is 22 to 60 nanometers. Only a small number oftiers 20 and 22 is shown, with more likely stack 18 comprising dozens, ahundred or more, etc. of tiers 20 and 22. Other circuitry that may ormay not be part of peripheral and/or control circuitry may be betweenconductor tier 16 and stack 18. For example, multiplevertically-alternating tiers of conductive material and insulativematerial of such circuitry may be below a lowest of the conductive tiers22 and/or above an uppermost of the conductive tiers 22. For example,one or more select gate tiers (not shown) may be between conductor tier16 and the lowest conductive tier 22 and one or more select gate tiersmay be above an uppermost of conductive tiers 22. Regardless, conductivetiers 22 (alternately referred to as first tiers) may not compriseconducting material and insulative tiers 20 (alternately referred to assecond tiers) may not comprise insulative material or be insulative atthis point in processing in conjunction with the herebyinitially-described example method embodiment which is “gate-last” or“replacement-gate”. Example conductive tiers 22 comprise first material26 (e.g., silicon nitride) which may be wholly or partially sacrificial.Example insulative tiers 20 comprise second material 24 (e.g., silicondioxide) that is of different composition from that of first material 26and which may be wholly or partially sacrificial.

Channel openings 25 have been formed (e.g., by etching) throughinsulative tiers 20 and conductive tiers 22 to conductor tier 16. Insome embodiments, channel openings 25 may go partially into conductivematerial 17 of conductor tier 16 as shown or may stop there-atop (notshown). Alternately, as an example, channel openings 25 may stop atop orwithin the lowest insulative tier 20. A reason for extending channelopenings 25 at least to conductive material 17 of conductor tier 16 isto assure direct electrical coupling of subsequently-formed channelmaterial (not yet shown) to conductor tier 16 without using alternativeprocessing and structure to do so when such a connection is desired.Etch-stop material (not shown) may be within or atop conductive material17 of conductor tier 16 to facilitate stopping of the etching of channelopenings 25 relative to conductor tier 16 when such is desired. Suchetch-stop material may be sacrificial or non-sacrificial. By way ofexample and for brevity only, channel openings 25 are shown as beingarranged in groups or columns of staggered rows of four and fiveopenings 25 per row and being arrayed in laterally-spaced memory-blockregions 58 that will comprise laterally-spaced memory blocks 58 in afinished circuitry construction. In this document, “block” is generic toinclude “sub-block”. Memory-block regions 58 and resultant memory blocks58 (not yet shown) may be considered as being longitudinally elongatedand oriented, for example along a direction 55. Memory-block regions 58may otherwise not be discernable at this point of processing. Anyalternate existing or future-developed arrangement and construction maybe used.

Transistor channel material may be formed in the individual channelopenings elevationally along the insulative tiers and the conductivetiers, thus comprising individual channel-material strings, which isdirectly electrically coupled with conductive material in the conductortier. Individual memory cells of the example memory array being formedmay comprise a gate region (e.g., a control-gate region) and a memorystructure laterally between the gate region and the channel material. Inone such embodiment, the memory structure is formed to comprise acharge-blocking region, storage material (e.g., charge-storagematerial), and an insulative charge-passage material. The storagematerial (e.g., floating gate material such as doped or undoped siliconor charge-trapping material such as silicon nitride, metal dots, etc.)of the individual memory cells is elevationally along individual of thecharge-blocking regions. The insulative charge-passage material (e.g., aband gap-engineered structure having nitrogen-containing material [e.g.,silicon nitride] sandwiched between two insulator oxides [e.g., silicondioxide]) is laterally between the channel material and the storagematerial.

FIGS. 3, 3A, 4 and 4A show one embodiment wherein charge-blockingmaterial 30, storage material 32, and charge-passage material 34 havebeen formed in individual channel openings 25 elevationally alonginsulative tiers 20 and conductive tiers 22. Transistor materials 30,32, and 34 (e.g., memory cell materials) may be formed by, for example,deposition of respective thin layers thereof over stack 18 and withinindividual channel openings 25 followed by planarizing such back atleast to a top surface of stack 18. Channel material 36 has also beenformed in channel openings 25 elevationally along insulative tiers 20and conductive tiers 22, thus comprising individual operativechannel-material strings 53. Materials 30, 32, 34, and 36 arecollectively shown as and only designated as material 37 in FIGS. 3 and4 due to scale. Example channel materials 36 include appropriately-dopedcrystalline semiconductor material, such as one or more silicon,germanium, and so-called III/V semiconductor materials (e.g., GaAs, InP,GaP, and GaN). Example thickness for each of materials 30, 32, 34, and36 is 25 to 100 Angstroms. Punch etching may be conducted as shown toremove materials 30, 32, and 34 from the bases of channel openings 25 toexpose conductor tier 16 such that channel material 36 is directlyagainst conductive material 17 of conductor tier 16. Such punch etchingmay occur separately with respect to each of materials 30, 32, and 34(as shown) or may occur collectively with respect to all afterdeposition of material 34 (not shown). Alternately, and by way ofexample only, no punch etching may be conducted and channel material 36may be directly electrically coupled to conductive material 17 ofconductor tier 16 by a separate conductive interconnect (not shown).Channel openings 25 are shown as comprising a radially-central soliddielectric material 38 (e.g., spin-on-dielectric, silicon dioxide,and/or silicon nitride). Alternately, and by way of example only, theradially-central portion within channel openings 25 may include voidspace(s) (not shown) and/or be devoid of solid material (not shown).Conductive plugs (not shown) may be formed atop channel material strings53 for better conductive connection to overlying circuitry (not shown).

Referring to FIGS. 5 and 6, horizontally-elongated trenches 40 have beenformed (e.g., by anisotropic etching) into stack 18 to formlaterally-spaced memory-block regions 58. Horizontally-elongatedtrenches 40 may have respective bottoms that are directly againstconductive material 17 (e.g., atop or within) of conductor tier 16 (asshown) or may have respective bottoms that are above conductive material17 of conductor tier 16 (not shown) Horizontally-elongated trenches 40may be considered as comprising sides 45.

The above processing shows forming and filling channel openings 25 priorto forming trenches 40. Such could be reversed. Alternately, trenches 40could be formed in between the forming and filling of channel openings25 (not ideal).

Referring to FIGS. 7-9, and in one embodiment, material 26 (not shown)of conductive tiers 22 has been removed, for example by beingisotropically etched away through trenches 40 ideally selectivelyrelative to the other exposed materials (e.g., using liquid or vaporH₃PO₄ as a primary etchant where material 26 is silicon nitride, andother materials comprise one or more oxides or polysilicon). Material 26in conductive tiers 22 in the example embodiment is sacrificial and hasbeen replaced with conducting material 48, and which has thereafter beenremoved from trenches 40, thus forming individual conductive lines 29(e.g., wordlines) and elevationally-extending strings 49 of individualtransistors and/or memory cells 56. Conducting material 48 may belaterally-recessed back within conductive tiers 22 from trench sides 45(as shown) to assure vertical separation of individual conductive lines29 relative one another. A thin insulative liner (e.g., Al₂O₃ and notshown) may be formed before forming conducting material 48.

Approximate locations of transistors and/or memory cells 56 areindicated with a bracket in FIG. 9 and some with dashed outlines inFIGS. 7 and 8, with transistors and/or memory cells 56 being essentiallyring-like or annular in the depicted example. Alternately, transistorsand/or memory cells 56 may not be completely encircling relative toindividual channel openings 25 such that each channel opening 25 mayhave two or more elevationally-extending strings 49 (e.g., multipletransistors and/or memory cells about individual channel openings inindividual conductive tiers with perhaps multiple wordlines per channelopening in individual conductive tiers, and not shown). Conductingmaterial 48 may be considered as having terminal ends 50 (FIG. 9)corresponding to control-gate regions 52 of individual transistorsand/or memory cells 56. Control-gate regions 52 in the depictedembodiment comprise individual portions of individual conductive lines29. Materials 30, 32, and 34 may be considered as a memory structure 65that is laterally between control-gate region 52 and channel material36. In one embodiment and as shown with respect to the example“gate-last” processing, conducting material 48 of conductive tiers 22 isformed after forming trenches 40. Alternately, the conducting materialof the conductive tiers may be formed before forming trenches 40 (notshown) and/or before forming channel openings 25, for example withrespect to “gate-first” processing.

A charge-blocking region (e.g., charge-blocking material 30) is betweenstorage material 32 and individual control-gate regions 52. A chargeblock may have the following functions in a memory cell: in a programmode, the charge block may prevent charge carriers from passing out ofthe storage material (e.g., floating-gate material, charge-trappingmaterial, etc.) toward the control gate, and in an erase mode the chargeblock may prevent charge carriers from flowing into the storage materialfrom the control gate. Accordingly, a charge block may function to blockcharge migration between the control-gate region and the storagematerial of individual memory cells. An example charge-blocking regionas shown comprises insulator material 30. By way of further examples, acharge-blocking region may comprise a laterally (e.g., radially) outerportion of the storage material (e.g., material 32) where such storagematerial is insulative (e.g., in the absence of anydifferent-composition material between an insulative storage material 32and conducting material 48). Regardless, as an additional example, aninterface of a storage material and conductive material of a controlgate may be sufficient to function as a charge-blocking region in theabsence of any separate-composition-insulator material 30. Further, aninterface of conducting material 48 with material 30 (when present) incombination with insulator material 30 may together function as acharge-blocking region, and as alternately or additionally may alaterally-outer region of an insulative storage material (e.g., asilicon nitride material 32). An example material 30 is one or more ofsilicon hafnium oxide and silicon dioxide.

A wall is formed in individual of the trenches laterally-betweenimmediately-laterally-adjacent of the memory-block regions, for exampleand in some embodiments as is described with reference to FIGS. 10-13.

Referring to FIG. 10, sides 45 of trenches 40 have been lined withinsulative material 70 that comprises at least one of an insulativenitride and elemental-form boron. In one embodiment, the insulativematerial comprises an insulative nitride, in one embodimentelemental-form boron, and in one embodiment both. In one embodiment, theinsulative nitride comprises one or more of silicon nitride, boronnitride, carbon nitride, silicon nitride carbide, and germanium nitride.In one embodiment and as shown, the at least one of insulative nitrideand elemental-form boron is formed directly against conducting material48 of conductive lines 29 and in one embodiment is devoid (i.e., from 0to no more than 0.1 atomic percent) of oxygen. Some prior art methodsand constructions formed silicon dioxide directly againstelemental-form-tungsten-conducting material 48 which undesirably causedformation of tungsten oxide. Using an insulative material comprising aninsulative nitride and/or elemental-form boron, particularly where theinsulative material is devoid of oxygen, may at least reduce or eveneliminate oxide formation.

In one embodiment, individual trenches 40 are formed to have anuppermost minimum lateral width in a vertical cross-section, for examplesuch width W in the vertical cross-section that is the plane of the pageupon which FIG. 10 lies. In such embodiment, insulative material 70 oneach side of core material 57 has a lateral width of 1% to 20% ofuppermost minimum lateral width W in the vertical cross-section.

Referring to FIGS. 11 and 12, a core material 57 has been formed intrenches 40 to span laterally-between the at least one of the insulativenitride and the elemental-form boron 70, thus forming a wall 75 inindividual trenches 40 laterally-between immediately-laterally-adjacentmemory-block regions 58. In one embodiment and as shown, core material57 is formed directly against the at least one of the insulative nitrideand the elemental-form boron. In one embodiment, core material 57 atleast predominately (i.e., more than 50 up to and including 100 atomicpercent) comprises insulative material, in another embodiment at leastpredominately comprises conductive material, and in still anotherembodiment at least predominately comprises semiconductive material.Example conductive materials include metal material andconductively-doped semiconductive material, for exampleconductively-doped elemental-form silicon, conductively-dopedelemental-form germanium, a conductively-doped alloy of silicon andgermanium, conductive elemental metals (e.g., W) conductive metalnitrides (e.g., TiN), and conductive metal oxides (e.g., indium oxide,ruthenium oxide, etc.). Example insulative core materials includeinsulative oxides, for example aluminum oxide, silicon dioxide, tantalumoxide, cupric oxide, cuprous oxide, iron oxide, and ferroelectricoxides. Example semiconductive materials include undoped orsemiconductively-doped elemental-form silicon, undoped orsemiconductively-doped elemental-form germanium, and an undoped orsemiconductively-doped alloy of silicon and germanium.

In one embodiment, core material 57 is homogenous. In anotherembodiment, core material 57 is not homogenous. For example, and by wayof example only, core material 57 may comprise a laterally-outerinsulative oxide (e.g., any of those stated above) and a laterally-innermaterial (i.e., laterally inward thereof) that is not an insulativeoxide (e.g., any one or more of insulative, conductive, andsemiconductive materials as described above). Further, core material 57may comprise void space (not shown), for example having one or more voidspaces of any size or shape internally there-within (not shown). In oneideal embodiment, insulative material 70 comprises silicon nitridedirectly against conducting material 48 and core material 57 compriseslaterally-outer silicon dioxide directly (the same, less, or greaterthickness as insulative material 70) against the silicon nitride andlaterally-inner undoped or lightly-doped (ideally not conductivelydoped) polysilicon directly against the silicon dioxide.

FIG. 13 shows subsequent processing whereby materials 70 and 57 havebeen planarized back at least to an elevationally outermost surface ofstack 18, thereby forming the example-finished-construction walls 75within trenches 40.

Alternate embodiment constructions may result from method embodimentsdescribed above, or otherwise. Regardless, embodiments of the inventionencompass memory arrays independent of method of manufacture.Nevertheless, such memory arrays may have any of the attributes asdescribed herein in method embodiments. Likewise, the above-describedmethod embodiments may incorporate, form, and/or have any of theattributes described with respect to device embodiments.

Embodiments of the invention include a memory array (e.g., 12)comprising strings of memory cells. The memory array comprises avertical stack (e.g., 18) comprising alternating insulative tiers (e.g.,20) and conductive tiers (e.g., 22). The conductive tiers individuallycomprise conductive lines (e.g., 29). Strings (e.g., 49) of memory cells(e.g., 56) in the stack comprise channel material (e.g., 36) extendingthrough the insulative tiers and the conductive tiers. Individual of thememory cells comprise the channel material, a gate region (e.g., 52)that is part of one of the conductive lines in individual of theconductive tiers, and a memory structure (e.g., 65) laterally-betweenthe gate region and the channel material in the individual conductivetiers.

Walls (e.g., 75) individually extend through the insulative tiers andthe conductive tiers laterally between immediately-adjacent of theconductive lines. The walls individually comprise laterally-outerinsulative material (e.g., 70) and a core material (e.g., 57) spanninglaterally-between the laterally-outer insulative material. Thelaterally-outer insulative material comprises at least one of aninsulative nitride and elemental-form boron.

Any other attribute(s) or aspect(s) as shown and/or described hereinwith respect to other embodiments may be used.

The above processing(s) or construction(s) may be considered as beingrelative to an array of components formed as or within a single stack orsingle deck of such components above or as part of an underlying basesubstrate (albeit, the single stack/deck may have multiple tiers).Control and/or other peripheral circuitry for operating or accessingsuch components within an array may also be formed anywhere as part ofthe finished construction, and in some embodiments may be under thearray (e.g., CMOS under-array). Regardless, one or more additional suchstack(s)/deck(s) may be provided or fabricated above and/or below thatshown in the figures or described above. Further, the array(s) ofcomponents may be the same or different relative one another indifferent stacks/decks and different stacks/decks may be of the samethickness or of different thicknesses relative one another. Interveningstructure may be provided between immediately-vertically-adjacentstacks/decks (e.g., additional circuitry and/or dielectric layers).Also, different stacks/decks may be electrically coupled relative oneanother. The multiple stacks/decks may be fabricated separately andsequentially (e.g., one atop another), or two or more stacks/decks maybe fabricated at essentially the same time.

The assemblies and structures discussed above may be used in integratedcircuits/circuitry and may be incorporated into electronic systems. Suchelectronic systems may be used in, for example, memory modules, devicedrivers, power modules, communication modems, processor modules, andapplication-specific modules, and may include multilayer, multichipmodules. The electronic systems may be any of a broad range of systems,such as, for example, cameras, wireless devices, displays, chip sets,set top boxes, games, lighting, vehicles, clocks, televisions, cellphones, personal computers, automobiles, industrial control systems,aircraft, etc.

In this document unless otherwise indicated, “elevational”, “higher”,“upper”, “lower”, “top”, “atop”, “bottom”, “above”, “below”, “under”,“beneath”, “up”, and “down” are generally with reference to the verticaldirection. “Horizontal” refers to a general direction (i.e., within 10degrees) along a primary substrate surface and may be relative to whichthe substrate is processed during fabrication, and vertical is adirection generally orthogonal thereto. Reference to “exactlyhorizontal” is the direction along the primary substrate surface (i.e.,no degrees there-from) and may be relative to which the substrate isprocessed during fabrication. Further, “vertical” and “horizontal” asused herein are generally perpendicular directions relative one anotherand independent of orientation of the substrate in three-dimensionalspace. Additionally, “elevationally-extending” and “extend(ing)elevationally” refer to a direction that is angled away by at least 45°from exactly horizontal. Further, “extend(ing) elevationally”,“elevationally-extending”, “extend(ing) horizontally”,“horizontally-extending” and the like with respect to a field effecttransistor are with reference to orientation of the transistor's channellength along which current flows in operation between the source/drainregions. For bipolar junction transistors, “extend(ing) elevationally”“elevationally-extending”, “extend(ing) horizontally”,“horizontally-extending” and the like, are with reference to orientationof the base length along which current flows in operation between theemitter and collector. In some embodiments, any component, feature,and/or region that extends elevationally extends vertically or within10° of vertical.

Further, “directly above”, “directly below”, and “directly under”require at least some lateral overlap (i.e., horizontally) of two statedregions/materials/components relative one another. Also, use of “above”not preceded by “directly” only requires that some portion of the statedregion/material/component that is above the other be elevationallyoutward of the other (i.e., independent of whether there is any lateraloverlap of the two stated regions/materials/components). Analogously,use of “below” and “under” not preceded by “directly” only requires thatsome portion of the stated region/material/component that is below/underthe other be elevationally inward of the other (i.e., independent ofwhether there is any lateral overlap of the two statedregions/materials/components).

Any of the materials, regions, and structures described herein may behomogenous or non-homogenous, and regardless may be continuous ordiscontinuous over any material which such overlie. Where one or moreexample composition(s) is/are provided for any material, that materialmay comprise, consist essentially of, or consist of such one or morecomposition(s). Further, unless otherwise stated, each material may beformed using any suitable existing or future-developed technique, withatomic layer deposition, chemical vapor deposition, physical vapordeposition, epitaxial growth, diffusion doping, and ion implanting beingexamples.

Additionally, “thickness” by itself (no preceding directional adjective)is defined as the mean straight-line distance through a given materialor region perpendicularly from a closest surface of animmediately-adjacent material of different composition or of animmediately-adjacent region. Additionally, the various materials orregions described herein may be of substantially constant thickness orof variable thicknesses. If of variable thickness, thickness refers toaverage thickness unless otherwise indicated, and such material orregion will have some minimum thickness and some maximum thickness dueto the thickness being variable. As used herein, “different composition”only requires those portions of two stated materials or regions that maybe directly against one another to be chemically and/or physicallydifferent, for example if such materials or regions are not homogenous.If the two stated materials or regions are not directly against oneanother, “different composition” only requires that those portions ofthe two stated materials or regions that are closest to one another bechemically and/or physically different if such materials or regions arenot homogenous. In this document, a material, region, or structure is“directly against” another when there is at least some physical touchingcontact of the stated materials, regions, or structures relative oneanother. In contrast, “over”, “on”, “adjacent”, “along”, and “against”not preceded by “directly” encompass “directly against” as well asconstruction where intervening material(s), region(s), or structure(s)result(s) in no physical touching contact of the stated materials,regions, or structures relative one another.

Herein, regions-materials-components are “electrically coupled” relativeone another if in normal operation electric current is capable ofcontinuously flowing from one to the other and does so predominately bymovement of subatomic positive and/or negative charges when such aresufficiently generated. Another electronic component may be between andelectrically coupled to the regions-materials-components. In contrast,when regions-materials-components are referred to as being “directlyelectrically coupled”, no intervening electronic component (e.g., nodiode, transistor, resistor, transducer, switch, fuse, etc.) is betweenthe directly electrically coupled regions-materials-components.

Any use of “row” and “column” in this document is for convenience indistinguishing one series or orientation of features from another seriesor orientation of features and along which components have been or maybe formed. “Row” and “column” are used synonymously with respect to anyseries of regions, components, and/or features independent of function.Regardless, the rows may be straight and/or curved and/or paralleland/or not parallel relative one another, as may be the columns.Further, the rows and columns may intersect relative one another at 90°or at one or more other angles.

The composition of any of the conductive/conductor/conducting materialsherein may be metal material and/or conductively-dopedsemiconductive/semiconductor/semiconducting material. “Metal material”is any one or combination of an elemental metal, any mixture or alloy oftwo or more elemental metals, and any one or more conductive metalcompound(s).

Herein, any use of “selective” as to etch, etching, removing, removal,depositing, forming, and/or formation is such an act of one statedmaterial relative to another stated material(s) so acted upon at a rateof at least 2:1 by volume. Further, any use of selectively depositing,selectively growing, or selectively forming is depositing, growing, orforming one material relative to another stated material or materials ata rate of at least 2:1 by volume for at least the first 75 Angstroms ofdepositing, growing, or forming.

Unless otherwise indicated, use of “or” herein encompasses either andboth.

CONCLUSION

In some embodiments, a method used in forming a memory array comprisingstrings of memory cells comprises forming a stack comprisingvertically-alternating first tiers and second tiers.Horizontally-elongated trenches are formed into the stack to formlaterally-spaced memory-block regions. A wall is formed in individual ofthe trenches laterally-between immediately-laterally-adjacent of thememory-block regions. The forming of the wall comprises lining sides ofthe trenches with insulative material comprising at least one of aninsulative nitride and elemental-form boron. A core material is formedin the trenches to span laterally-between the at least one of theinsulative nitride and the elemental-form boron.

In some embodiments, a method used in forming a memory array comprisingstrings of memory cells comprises forming a stack comprisingvertically-alternating first tiers and second tiers.Horizontally-elongated trenches are formed into the stack to formlaterally-spaced memory-block regions. Through the trenches, sacrificialmaterial that is in the first tiers is isotropically etched away andreplaced with conducting material of individual conductive lines.Individual memory cells of the strings of memory cells are formed tocomprise channel material of channel-material strings in thememory-block regions, a gate region that is part of one of theindividual conductive lines in individual of the first tiers, and amemory structure laterally-between the gate region and the channelmaterial of the channel-material strings in the individual first tiers.The channel-material strings are formed before forming the conductingmaterial of the individual conductive lines. After the replacing, a wallin individual of the trenches is formed laterally-betweenimmediately-laterally-adjacent of the memory-block regions. The formingof the wall comprises lining sides of the trenches with insulativematerial comprising at least one of an insulative nitride andelemental-form boron that is directly against the conducting material ofthe individual conductive lines. A core material is formed in thetrenches spanning laterally between the at least one of the insulativenitride and the elemental-form boron. The forming of the core materialcomprises forming a laterally-outer silicon dioxide that is directlyagainst said at least one of insulative nitride and elemental-formboron. Polysilicon is formed directly against and spanslaterally-between said laterally-outer silicon dioxide.

In some embodiments, a memory array comprising strings of memory cellscomprises a vertical stack comprising alternating insulative tiers andconductive tiers. The conductive tiers individually comprise conductivelines. Strings of memory cells in the stack comprise channel materialthat extends through the insulative tiers and the conductive tiers.Individual of the memory cells comprise the channel material, a gateregion that is part of one of the conductive lines in individual of theconductive tiers, and a memory structure laterally-between the gateregion and the channel material in the individual conductive tiers.Walls individually extend through the insulative tiers and theconductive tiers laterally between immediately-adjacent of theconductive lines. The walls individually comprise laterally-outerinsulative material and a core material spanning laterally-between thelaterally-outer insulative material. The laterally-outer insulativematerial comprises at least one of an insulative nitride andelemental-form boron.

In some embodiments, a memory array comprising strings of memory cellscomprises a vertical stack comprising alternating insulative tiers andconductive tiers. The conductive tiers individually comprise conductivelines comprising conducting material. Strings of memory cells in thestack comprise channel material that extends through the insulativetiers and the conductive tiers. Individual of the memory cells comprisethe channel material, a gate region that is part of one of theconductive lines in individual of the conductive tiers, and a memorystructure laterally-between the gate region and the channel material inthe individual conductive tiers. Walls individually extend through theinsulative tiers and the conductive tiers laterally-between two of theconductive lines. The walls individually comprise laterally-outerinsulative material and a core material spanning laterally-between thelaterally-outer insulative material. The laterally-outer insulativematerial comprises at least one of an insulative nitride andelemental-form boron that is directly against the conducting material ofthe conductive lines. The core material comprises a laterally-outersilicon dioxide that is directly against said at least one of insulativenitride and elemental-form boron. Polysilicon is directly against andspans laterally-between said laterally-outer silicon dioxide.

In compliance with the statute, the subject matter disclosed herein hasbeen described in language more or less specific as to structural andmethodical features. It is to be understood, however, that the claimsare not limited to the specific features shown and described, since themeans herein disclosed comprise example embodiments. The claims are thusto be afforded full scope as literally worded, and to be appropriatelyinterpreted in accordance with the doctrine of equivalents.

The invention claimed is:
 1. A method used in forming a memory arraycomprising strings of memory cells, comprising: forming a stackcomprising vertically-alternating first tiers and second tiers; forminghorizontally-elongated trenches into the stack to form laterally-spacedmemory-block regions; forming a wall in individual of the trencheslaterally-between immediately adjacent of the laterally-spacedmemory-block regions, the forming of the wall comprising: lining sidesof trenches with insulative material comprising at least one insulativenitride and elemental-form boron; and forming a core material in thetrenches to span laterally-between the insulative material.
 2. Themethod of claim 1 wherein the insulative material comprises one or moremembers of the group consisting of silicon nitride, boron nitride,carbon nitride, silicon nitride carbide, and germanium nitride.
 3. Themethod of claim 1 wherein the insulative material is devoid of oxygen.4. The method of claim 1 comprising: before forming the wall in theindividual trenches, isotropically etching away and replacingsacrificial material that is in the first tiers with conducting materialof individual conductive lines; forming individual memory cells of thestrings of memory cells to comprise channel material of channel-materialstrings in the memory-block regions, a gate region that is part of oneof the individual conductive lines in individual of the first tiers, anda memory structure laterally-between the gate region and the channelmaterial of the channel-material strings in the individual first tiers,forming the channel-material strings before forming the conductingmaterial of the individual conductive lines; and after the replacing,forming the wall in the individual trenches.
 5. A method used in forminga memory array comprising strings of memory cells, comprising: forming astack comprising vertically-alternating first tiers and second tiers;forming horizontally-elongated trenches into the stack to formlaterally-spaced memory-block regions; forming a wall in individual ofthe trenches between immediately adjacent of the laterally-spacedmemory-block regions, the forming of the wall comprising: lining sidesof trenches with insulative material comprising an insulative nitrideand optionally elemental-form boron; and forming a core material in thetrenches to span laterally-between the insulative material, theindividual trenches having an uppermost minimum lateral width in avertical cross-section, the insulative material on each side of the corematerial having a lateral width of 1% to 20% of the uppermost minimumlateral width in the vertical cross-section.
 6. A method used in forminga memory array comprising strings of memory cells, comprising: forming astack comprising vertically-alternating first tiers and second tiers;forming horizontally-elongated trenches into the stack to formlaterally-spaced memory-block regions; through the trenches,isotropically etching away and replacing sacrificial material that is inthe first tiers with conducting material of individual conductive lines;forming individual memory cells of the strings of memory cells tocomprise channel material of channel-material strings in thememory-block regions, a gate region that is part of one of theindividual conductive lines in individual of the first tiers, and amemory structure laterally-between the gate region and the channelmaterial of the channel-material strings in the individual first tiers,forming the channel-material strings before forming the conductingmaterial of the individual conductive lines; after the replacing,forming a wall in individual of the trenches laterally-betweenimmediately adjacent of the laterally-spaced memory-block regions, theforming of the wall comprising: lining sides of trenches with insulativematerial comprising at least one insulative nitride and elemental-formboron that is directly against the conducting material of the individualconductive lines; and forming a core material in the trenches spanninglaterally between the insulative material, the forming of the corematerial comprising: forming a laterally-outer silicon dioxide that isdirectly against said at least one of insulative nitride andelemental-form boron; and forming polysilicon directly against and tospan laterally-between said laterally-outer silicon dioxide.